Best string for Babolat Pure strom gt and Head youtek prestige mp

Hello,
I just posted a thread on the racquet category regarding Pure strom gt vs Head youtek prestige mp racquet......
Okay, my mane is Manolo I'm Italian I'm a 4.5 tennis player and 37 yeras old currently using the Babolat pure storm gt. I'm a baseline player who does not mind at all to attack and to go to net. I'm a pretty aggressive player who looks for winner with the forhand and backhand. I hit with topsping (not extreme)and flat shots as well especially when I go for the winner along the line. I'm mostly a double hands back hand but I hit slice too. I restarted playing tennis after a very long time in May 2009 picking Babolat as my stick since I had a good feeling with it....I started off with the Pure drive team, then the Aeropro drive cortex and finally the Pure strom gt. I really like the Pure strom gt (yet nor really much the string on currently stung at 50lbs with pro plasma)even though I can get the best out of it yet because I still playing with the string and tension.

Can you guys help me out to find the right string and tension?

I'm thinking also to buy a Head youtek prestige mp so any suggestion about string and tension ?